LOS ANGELES - Canadian Melissa Vatkin has joined thousands of couples flocking to the United States to cash in on the disputed luxury of being able to dictate the sex of their next baby.

LOS ANGELES - Canadian Melissa Vatkin has joined thousands of couples flocking to the United States to cash in on the disputed luxury of being able to dictate the sex of their next baby.

Parents from around the world are forking out around US$19,000 for a groundbreaking gender selection treatment offered by only a handful of U.S. clinics that are banned in most countries.

The high-tech method of resolving the ancient question of "Would we prefer a boy or a girl?" has raised ethical concerns and fears that it could worsen an already worrying gender imbalance plaguing countries such as China and India.

But for couples like the Vatkins, pre-implantation genetic diagnosis (PGD), which proponents boast gives parents a 99% certainty of delivering a baby of the sex of their choice, the procedure is a godsend.

"This treatment has allowed us to realize our dream," said 36-year-old Ms. Vatkin, who recently gave birth to her fourth child, a pre-selected girl.

"We were desperate to have another girl and our daughter really wanted a sister," said Ms. Vatkin, who also has a six-year-old daughter and two boys, aged four and two, with her husband Shawn, an oil company owner.

"It was important for us to balance our family," added the resident of Vancouver.

Family balancing is the refrain heard from most of the 2,000 couples who have sought the help of fertility expert Dr. Jeffrey Steinberg, who became a pioneer in the field of commercial gender selection about three years ago.

"Usually these couples have four of five children of one sex and desperately want one of the opposite sex, they want to balance their families in a way that works for them," Dr. Steinberg told Agence France Presse

For more than two years, the Vatkins, children in tow, made the 2,100-kilometre pilgrimage from their home to Steinberg's Fertility Institute in Los Angeles in a bid to overcome their fertility problems and to ensure that when the baby did come, it would be a girl.

Other couples come from much further afield. More than 50% of the couples that come to Dr. Steinberg for help are from outside the United States.

"They come from everywhere that it's banned by law," Dr. Steinberg said. "But in the United States we really guard and cherish reproductive choice and we are very reticent to allow the government to impinge on that."

Using techniques made possible by the discovery of the human genome, eggs are removed from the mother after she undergoes fertility treatment to multiply them and are fertilized with the would-be father's sperm in a laboratory dish.

One of the cells in each embryo is then removed to allow scientists to determine from its DNA whether the embryo is male or female, before one of the desired gender is implanted into the mother's womb to gestate.

But some bioethicists say the technique could aggravate gender imbalances in some communities and could be the start of a slide towards designer babies and cloning if parents are ever able to pre-select their children's hair colour or personal talents.

In countries such as China and India, boys are culturally favoured as first children, abortions of fetuses following amniocentesis gender tests and even infanticide have combined to see a huge decline in the birthrate of girls.

"In some places, the impact for sex ratios would be pretty dramatic if people had the complete power to chose the gender of their child," said Stanford University bioethicist David Magnus.

He however stressed that because PGD was an expensive and complex technique, it was unlikely to be widely used either in the developing world or even in the United States.

But there may be a risk of creating a culture of perfectly-planned "designer babies," he warned.

"With new technology, there are fears that we may be heading towards a future where only the poor are fat or bald, that we are heading towards creating a genetic underclass and genetic overclass," Mr. Magnus said.

The process also rings alarm bells among conservative Christians amid concerns over the fate of unused embryos left over in the process, since many believe human life begins when the embryo is formed. But Dr. Steinberg dismissed the three-pronged criticism of the gender selection process.

He stressed that his clients mostly opt to keep fertilized eggs in his eggbank rather than discard them. He said the technique was more humane than the current trend of aborting fetuses or dumping female babies in India and China.

Overall, his clients were divided evenly over which sex they would prefer for the baby. Americans and Canadians favour girls, Indians and Chinese want boys, and Latin Americans are split.

Dr. Steinberg also denied that the technique was the start of a trend towards designer babies or even human cloning.

For the Vatkins, critics' fears are overplayed.

"This treatment really is miraculous for couples like us and especially for those who have, say, three girls and really want a boy," Ms. Vatkin said. "A lot of people don't agree, but then they shouldn't do it."

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